“Any expansion of the EU ETS to cover departing flights from Europe would reignite long-standing legal concerns about the extraterritorial application of EU law”. So said the latest position paper on the EU Emissions Trading System (ETS) from the International Air Transport Association (IATA). If you spend a lot of time in aviation climate policy discussions – as I have over the years, and as we do at Opportunity Green – you won’t fail to notice claims like this, often-repeated from incumbent industry voices when it comes to the revision of the EU ETS.
The industry claims that the Chicago Convention (the foundational treaty on international aviation, dated from 1944) is all-prevailing, and therefore only action at the international level is legitimate. As their theory goes, this means the UN’s aviation agency, the International Civil Aviation Organization (ICAO), is solely responsible for any legal regulation on aviation.
This message from industry is loud and consistent. Being ostensibly ‘legal’ in nature (and therefore difficult to engage with if you aren’t a legal expert yourself), these arguments can often be taken at face value by the people we most need to apply rigorous scrutiny – i.e. policymakers making tough decisions about how best to tackle climate change.
But apply that scrutiny, and these objections rapidly start to crumble. Scratch the surface, and what you discover is that courts have already grappled with these arguments and reached clear conclusions – just not in the way that the industry likes to claim.
Why the airlines’ arguments don’t hold up
When the EU first started to regulate the climate impact of all flights departing from or arriving at EU airports, the Air Transport Association of America (now Airlines for America) along with a number of individual US airlines, brought a court case stating that EU action on aviation climate violated international law.
The airlines claimed that the EU was not entitled to introduce legislation regulating emissions on flights into and out of the Union. It argued that the EU had ceded sovereignty to do so by virtue of signing up to the Chicago Convention and the Open Skies Agreement (an EU-US agreement on certain aviation issues).
The problem with this interpretation? It implies that the US, which is also a signatory to these agreements, had ceded that same sovereignty. This would be surprising to say the least, as the US ceding sovereignty isn’t a usual approach in the context of international treaties.
In fact, there is no international agreement where countries have come together to say that they will NOT regulate the climate impact (or indeed other impacts) of aircraft that stop in their countries.
On the contrary; in 2011 the European Court of Justice very clearly said the EU could require aircraft stopping at an EU airport to account for their climate impact. Put simply: if you want to land your aircraft in or take off from European territory, you are subject to European rules.
Since that ruling in 2011, nothing about the international law on aviation has significantly changed. But international climate law has.
The Paris Agreement requires national governments to look economy wide to reduce emissions in line with temperature goals, and yes, that includes emissions from international aviation. Individual countries are responsible for meeting that obligation. They might work through international agencies such as ICAO to do so, but the obligation remains their own – where ICAO action is not progressive enough, countries (or blocs) must act themselves.
Time to see through the delay, deny and deflect strategy
Since then, I have heard over and over from airlines that EU action on climate from aviation is illegal. But interestingly, I haven’t seen any actual legal analysis backing up this argument.
Indeed, when I was on a panel this June, I pointed to legal analysis we have done on aviation fuel taxation. This sets out the legal basis for putting a tax on aviation, demonstrating that the industry’s claims that a tax on kerosene is illegal under the Chicago Convention are unfounded.
In response, another panellist from IATA told me they would share their analysis proving such a tax is indeed illegal. In good faith, I sent our work across – but never received a reply. Of course, all the audience heard was the message, without the lack of underlying detail.
This is problematic because it happens time and again. It is the classic delay, deny and deflect strategy that has been used so effectively by the fossil fuel industry for decades to evade taking any meaningful climate action. Indeed, this is clearly set out by InfluenceMap in their 2026 briefing on the lobbying of the aviation sector.
Meanwhile, in August 2026, Marie Owens Thomsen of IATA told Carbon Pulse that the latest revision to the EU ETS, “violates customary international law, and it violates the Chicago Convention”.
Conveniently, Thomsen fails to consider international climate obligations in her assessment, with no regard for the obligation to reduce emissions in line with the Paris Agreement. There was also no mention of the settled case law from 2011 on the exact same piece of legislation, where these exact arguments were considered and dismissed. What’s more indicative of industry’s baseless delay tactics is that our legal analysis clearly demonstrates that the ETS can be expanded in line with settled case law, and without infringing international law.
Meanwhile, the vast majority of experts in international aviation law will earn their money through airlines and so not be willing (even if they do agree) to set out the international law clearly. What is going on here is the classic political playbook. Airlines know full well that there are quite simply no legal issues with the ETS, but they bring this argument to the political domain regardless.
This is not a legal argument; it is political lobbying given a legal cover to make it appear legitimate. Let’s hope policymakers see through it and rely on the settled case law: there are no questions under international law around expanding the ETS.
